This disclosure relates, in various embodiments, to phenolic hole transport polymers and/or to electrostatographic imaging members utilizing the same, and more specifically, to imaging members having a layer containing phenolic hole transport polymers comprising a phenolic segment, a hole transport segment, and a divalent linkage.
Electrostatographic imaging members are known in the art. Typical electrostatographic imaging members include photoreceptors for electrophotographic imaging systems and electroreceptors such as ionographic imaging members for electrophotographic imaging systems. They have a number of different configurations. For example, they can comprise a flexible member, such as a flexible scroll or a belt, which may be seamed or unseamed. They can also be a rigid member, such as a rigid support substrate drum. Drum imaging members have a rigid cylindrical supporting substrate bearing one or more imaging layers.
An electrophotographic imaging member is imaged by uniformly depositing an electrostatic charge on the imaging surface of the electrophotographic imaging member and then exposing the imaging member to a pattern of activating electromagnetic radiation, such as light, which selectively dissipates the charge in the illuminated areas of the imaging member while leaving behind an electrostatic latent image in the non-illuminated areas. This electrostatic latent image may then be developed to form a visible image by depositing finely divided electroscopic marking toner particles on the imaging member surface. The resulting visible toner image can then be transferred to a suitable receiving member or substrate such as paper.
An electrophotographic imaging members may comprise a supporting substrate, a charge generating layer, a charge transport layer (“CTL”), and an optional overcoat layer (“OCL”). Depending on the design of the imaging member, either the CTL or an OCL will be the outermost layer and therefore the layer exposed to the operating environment of the imaging member.
The operating environment exposes the imaging member to several conditions which can decrease its service life. It is exposed to several airborne chemical contaminants. Typical chemical contaminants include solvent vapors, environment airborne pollutants, and corona species emitted by machine charging subsystems such as ozone. In some designs, such as a rigid drum design utilizing a contact AC Bias Charging Roller (BCR), ozone species attack on the imaging member can be even more pronounced because of the close vicinity of the BCR to the drum. It is also inevitably subjected to constant mechanical interactions against various electrophotographic imaging machine subsystems under a normal service environment. These mechanical interactions include abrasive contact with cleaning and/or spot blades, exposure to toner particles, carrier beads, toner image receiving substrates, etc. As a result, the imaging member may frequently exhibit mechanical failures such as frictional abrasion, wear, and surface cracking.
Because of environmental conditions, the outermost layer must be designed so that it can withstand those conditions yet still function effectively. Poor mechanical wear resistance may be attributed to the current design of some such layers, especially when the CTL is the outermost layer. A conventional CTL usually comprises a charge transport compound in a film-forming polymeric binder resin. Because the polymeric binder is usually electrically inactive, it is the charge transport compound which supports the injection and transport of photogenerated holes or electrons. An antioxidant is sometimes incorporated as well to reduce the effects of ozone exposure, which attacks the polymer bonds and breaks it down. However, high loading of such compounds adversely affects the electrical characteristics of the imaging member. In addition, oxidation of the charge transport compound, such as a hole transport molecule, arising from poor corona charging resistance can cause lateral charge migration (LCM). Image deletion may also occur. Antioxidants may also escape during heating of the outermost layer.
It is desired to provide a composition which balances good mechanical properties with good electrical and printing performance and which may also be used as a hole transport polymer.